Magnesium lamp for photographic purposes



May 16, 1933! w. BORTH 1,909,567

MAGNESIUM LAMP FOR PHOTOGRAPHIC PURPOSES Filed Jan. 6, 1931 Fig. .7 I

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/n venfor: Mu 75/? 5mm Patented May 16, 1933 imrrso STA WALTER BORTH, OFCHEMINITZ, GERMANY MAGNESIUM LAMP FOR PHOTQGRAPHIC PURPOSES Applicationfiled January 6, 1931, Serial No.

My invention relates to illuminating lamps to be used in takingphotographs, and more especially to lamps of the class in which thelightis produced by the combus- 5 tion of apiece of magnesium of likecombustible metal, which burns away within a relatively long period oftime-one or more secondswhen compared with the momentary andexplosiondike combustion ofcartridges containing flash lightpoWder-usually finished in about 1/50 secondas used in connection withwell-known but materially different classes of illuminating lamps.

Magnesium lamps are preferably used in many cases, especially for takingindoor photographs, because of the relatively small volume of theirflame, their low burning speed and the absence of hissing noise, whichare factors of safety and comfort: By reason of the comparatively longtime'of exposure-one second and longer--during which light produced bymagnesium lam s is active upon the photographic plate, on y a flame ofan accordingly small volume is required which yet has the samephotochemical effect as the many times more powerful illuminationnecessarily produced by flash light powderlamps in which the combustionlasts only about 1/50 second.

Persons to be photographed are therefore less likely to be dazzled andirritated by the light produced by magnesiumlamps; moreover strips ofwire of magnesium, in which form the latter is mostly used in practice,are altogether a more harmless illuminating medium than those cartridgesor bags containing flash light powder which are known to occasionallyemitsparks and cause considerable danger, e. g. to curious people,children etc. who inadvertently come too near the suddenly rising andrelatively large flame of a flash light lamp.

For obtaining an efficient illumination it has been customary heretoforeto use lamps in which a plurality of strips of magnesium aresimultaneously burnt; however, although those strips are usually rathernarrow and cut from thin magnesium foil in order to more easily catchfire and evenly burn away, their simultaneous ignition often causes an-507,006, and in Germany January 18, 1930.

noyance and disappointment, because of the tendency of the strips toroll up, and the working with magnesium lamps therefore calls in manycases for considerable skill and experience on the part of the operator.v It can happen that some of the strips of magnesium will not catch fireat all or do not start and do not finish burning at the same time, sothat their illuminating effect is considerably impaired.

The principal object of this invention is toprovide a structurallysimple and inexpensive magnesium lamp of improved design which can beeasily and safely manipulated even by unskilled operators, viz. amateursin the photographic art.

Another object of the invention is to thus design the magnesium lampthat the volume and intensity of the flame developed gradually increasesduring the illumination from zero to a maximum, so that the risk ofdazzling and irritating persons to be photo.- graphed is greatly reducedor eliminated.

Other objects of the invention will become apparent hereinafter.

The nature and scope of my invention'are briefly outlined in theappended claims and will be more fully understood from the followingspecification taken together with the accompanying drawing, in which anillumi nating lam and pieces of magnesium foil, to be used t erewith andexhibiting the salient features of this invention, are shown by way ofexamples. 7

Fig.1 is a front elevation of the lamp ready for use, partly shown insection taken on line 11 of Fig. 2,

Fig. 2 is' a plan, partly shown in section, taken on line 22 in Fig. 1,

Figs. 3-6 show a few modifications in the shape of the triangular pieceof magnesium' foil designed for the purposes of this invention.

Briefly described the improved magnesium lamp consists of asubstantially triangular piece of magnesium foil, a, of means forkeeping said piece of magnesium foil freely suspended in uprightposition with two of its corners at substantially the same height,'whilethe third corner presents its lowest point, and of means for ignitingsaid triangular piece of magnesium foil from below.

In the embodiment of my invention shown by way of an example in thedrawing the means for keeping the triangular piece of magnesium foilfreely suspended in the specified upright position comprises a cas ing1, open at the top,a cover (Z hin ed to said casing, so as to be capableof being" swung upwardly into an upr1ght pos1t1 on, v

a hoop b, hinged to said cover d at its inner side, so as to be capableof being swung out- Wardly and away from the cover dl, when the latteris in its upright position,'and slotted clamps 0 provided at the outerends. of the said hoop 6, into which the said tri-' angular piece ofmagnesium foil a is inserted with two of its corners.

In the embodiment of the invention shown by way of an exa'n ple in Figs.1 and 2 the means for igniting the triangular piece of magnesium foilcomprise a burner e, pivotally mounted at h withinthe casing 1' andspring actuated means under the control of the operator for moving theburner e from an idle position into its working position rightunderneath the lower corner 'of the triangular piece of magnesium foil.

out sheet of foil and is tapered towards one end. Preferably it has theform of an isosceles triangle, as shown in Fig; 1. The apex, which hangsdownwards, forms the point of ignition. The fastening to a holder 6 iseffected at the two corners of the base line. The combustible bodyholder 6 consists of a hoop open towards the front, which has at the twolateral ends small clamps o, in which the combustible body is lightlyclamped. The holder hoop is arranged'in a casing Z with the cover'd. Theholder hoop can preferably be rotatably mounted on the casing cover (Zby means of a bushing or tube m, in order to enable the lamp to befolded up and carried conveniently in the pocket. The inside of thecover is polished and serves as a reflector.

For igniting the combustible bod a a movable burner e is provided, whichis supported by a lever g. 'The lever is rotatable about a vertical axish and is connected to'a lever 2'. Between said lever and the verticalwall of the casing a spring is arranged.

The burner can be brought into the igniting position shown by a wirerelease f or by an automatic release or by clockwork.

Ignition of the combustible body a is effected by the flame of theburner e at the lower end and requires, by reason of the small amount tobe first heated and melted, only the shortest time, indeed 1 second calculated from the moment of hand operation, whilst with several strips,many times this amount of time is consumed during ignition.

.-unpleasant, so that unsightly closing of the eyes in photographingpersons is avoided.

Vario'us changes and modifications may be made in the structural detailsof illuminating'lamps of the improved design described above and also inthe specific shape of individual triangular pieces of magnesi'um foil tobe used therewith, without dea parting from the spirit and the leadingideas of my invention.

In order to modify the sharp contours of the shadows thrown, the sourceof light must also receive a sufiicient expansion. For this purpose thebase line of the triangular combustible body can have a greater breadth,whereby it is true, the apex angles would be increased and as aconsequence a delay in ig- The combustible body a; eons1sts of acutniting would follow. In order to prevent this, the sides of thetriangle whilst retaining the small apex angle, can be replaced bybroken lines or curves, so that shapes similar to that in Fig. 3 areobtained.

The upper base line can also be formed as a curve, in order to obtainapproximately equal distance from the point of ignitionto the furthestmetal parts of the base line and to produce as near as possible aburning of the whole, surface up to the end; The plane surface wouldthen be equal to or similar to a quadrant, as, for instance, shown inFig. 4.

The corners at the base line could also be made blunt or rounded, inorder to avoid damage when fixing up the thin foil, so that thetriangular or heart-like shapes shown as examples in Figs. 5 and 6 wouldbe obtained.

I am aware that apart from thin sheets or foils of magnesium, used asfuel for illuminating lamps, and of which triangular pieces are used inconnection. with this inventiona rapidly burning flash light composition is known in the art, which is mixed with a cementing materialand is spread out so as to form a foil: I make no claim neither toanyspecific flash light composition nor to its application in the formof a foil per se.

Neverthelessalthough simply magnesium'foil is specified above as beingthe material from which the triangular pieces are made, to be used inconnectionwith my invention, I do not wish to restrict myself to foilsof pure magnesium, in as much as foils made of appropriate alloys ofmagnesium, burning also at a relatively low rate of speed and producingbrilliant light may obviously be used instead and would givesubstantially the same illuminating effect of gradually increasing powerwhich is one of the main objects of my invention.

What I claim is:

1. In a magnesium lamp for photographic purposes, a casing, a holder insaid casing, a sheet of magnesium foil tapered towards its lower end,said sheet being suspended on said holder, a burner, a lever rotatablein a horizontal plane and supporting said burner, an operating leverconnected to said supporting lever and adapted to move said burner intoigniting position, and a spring between said operating lever and a wallof said casing, said spring being adapted to retract said burner fromits igniting position.

2. In a magnesium lamp for photographic purposes, a flat casing, a coverfor and rotatably connected to said casing, a hoop open toward the frontand rotatably mounted on the inside of said cover, clamps at the twofront lateral ends of said hoop, said clamps being adapted to sustain asheet of magnesium foil, and a movable burner in said casing forigniting said foil.

3. In a magnesium lamp for photographic. purposes, a horizontal flatcasing, a cover for said casing, said cover being rotatably connected tosaid casing and adapted to be brought into a vertical position, a hoopopen toward the front, said hoop being rotatably mounted on the insideof said casing and adapted to be brought to a horizontal position,clamps positioned at the two front lateral ends of said hoop, saidclamps being adapted to sustain a sheet of magnesium tapered towards itslower end, and a movable burner in said casing, said burner beingadapted to be moved from an inoperative position to the operativeposition below the tapered end of said foil.

4;. In a magnesium lamp for photographic purposes, a horizontal flatcasing, a cover for said casing, said cover being rotatably connected tosaid casing and adapted to be brought into a vertical position, and saidcover having a polished lower surface adapted to serve as a reflector, ahoop open toward the front, said hoop being rotatably mounted on theinside of said casing and adapted to be brought to a horizontalposition, clamps at the two front lateral ends of said hoop, said clampsbeing adapted to sustain a sheet of magnesium tapered towards its lowerend, and a movable burner in said casing, said burner being adapted tobe moved from an inoperative position to the operative position belowthe tapered end of said foil.

5. In a magnesium lamp for photographic purposes, a fiat casing, a coverfor and rotatably connected to said casing, a hoop open toward the frontand rotatably mounted on the inside of said cover, clamps at the twofront lateral ends of said hoop, a sheet of magnesium foil taperedtowards its lower end, said sheet being held by said clamps, and a leverrotatable in said casing, said lever supporting a burner adapted to bebrought under the lower end of said foil.

6. Illuminating lamp for the purpose set forth, comprising incombination a substantially triangular piece of combustible metal foil,burning at a relatively low rate of speed and producing brilliant light,means for keeping said piece of metal foil freely suspended in uprightposition with two of its corners being at substantially the same height,while its third corner presents the lowest point, and means for ignitingsaid piece of metal foil.

7 Illuminating lamp, having the features set forth in claim 6, in whichthe means for keeping the said triangular piece of metal foil freelysuspended in the specified position comprise-a casing open at the top, acover hinged to said casing, so as to be capable of being swung upwardlyinto an upright position, a hoop hinged to said cover at its inner side,so as to be capable of being swung outwardly and away from the cover,and slotted clamps provided at the outer ends of said hoop and beingadapted to receive the piece of metal foil, inserted thereinto with twoof its corners.

8. Illuminating lamp having the features set forth in claim 6, in whichthe means for igniting the metal foil comprise a burner, pivotalllymounted and being cooperatively associated with spring actuated meansunder the control of the operator for turning the said burner from anidle position into its Working position right underneath the metal foil.

In testimony whereof I have aflixed my signature.

WALTER BORTH.

